dude101 said:

I need help with graphing equations. I have 4 problems to do and they all have to do with the same thing. I dont want the answers, I just need to know how to work them out for future equations. Heres one of them.

Graph each equation. Find the slope, the x-intercept, and the y-intercept.

9. y= 2x - 6

When the equation of a line is in the form

y = mx + b

the slope and the y-intercept can be determined almost immediately. "m".....the coefficient of x....is the slope. "b"....the constant term.....is the y-intercept. This is called the "slope-intercept form" for the equation of a line.

Here's an example:

y = -2x + 5

The coefficient of x is -2, and this is the slope. The constant term is 5, so this is the y-intercept, at the point (0, 5).

If you want to find the x-intercept as well, remember that any point on the x-axis has a y-coordinate of 0. Substitute 0 for y, and solve for x:

0 = -2x + 5

2x = 5

x = 5/2, and the x-intercept is 5/2, or the point (5/2, 0).

Now, what if the equation is NOT in slope-intercept form? What if you have this equation:

3x + 4y = 12

No big deal! Just solve the equation for y. Add -3x to both sides to get

4y = -3x + 12

Divide both sides of the equation by 4:

y = (-3/4)x + 3

And the slope is -3/4. The y-intercept is 3, or the point (0, 3). To find the x-intercept, substitute 0 for y, and solve for x.

I hope this helps you with your problems.